The Ninth Circuit, sitting en banc, struck down a San Francisco ordinance that required health warnings on certain advertising for some types of sugar-sweetened drinks. 

San Francisco enacted its Sugar-Sweetened Beverage Warning Ordinance in 2015, which applies to non-alcoholic drinks with added sweeteners that contain more than 25 calories per 12 ounces.  The Ordinance requires that outdoor and transit advertisements include the following warning statement:  "WARNING:  Drinking beverages with added sugar(s) contributes to obesity, diabetes, and tooth decay.  This is a message from the City and County of San Francisco."   The warning must be large enough to occupy at least 20% of the advertisement and be set off with a rectangular border.  

San Francisco argued that the warning was necessary in order to "inform the public of the presence of added sugars and thus promote informed consumer choice that may result in reduced caloric intake and improved diet and health."  

The American Beverage Association, the California Retailers Association, and the California State Outdoor Advertising Association sued the City and County of San Francisco, alleging that the ordinance violated the First Amendment.  The district court denied the plaintiffs' motion for a preliminary injunction.  The 9th Circuit reversed, and then ordered that the case be heard en banc. 

In order to determine whether the disclosure requirement violated the First Amendment, the 9th Circuit asks whether compelled disclosure is "reasonably related to a substantial government interest."  In order to determine this, the court must determine whether the disclosure is (1) purely factual, (2) noncontroversial, and (3) not unjustified or unduly burdensome

The 9th Circuit held that the disclosure requirement violated the First Amendment because San Francisco failed to prove that the disclosure requirement was "not unjustified or unduly burdensome."  Focusing on the requirement that the disclosure be at least 20% of the size of the advertisement, the court found that San Francisco was not able to prove that it was necessary that the disclosure be that big.  The court wrote, "the record here shows that a smaller warning -- half the size -- would accomplish Defendant's stated goals."  Therefore, the court held that the requirement was not justified, in light of its potential to chill protected speech.